Method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride from sodium fluosilicate acidified by sulfuric acid

Abstract

The invention provides a method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride from sodium fluosilicate acidified by sulfuric acid, which relates to the technical field of fluorine chemical industry, in particular to a method for preparing silicon tetrafluoride gas and anhydrous hydrogen fluoride gas by reaction of sodium fluosilicate and sulfuric acid. The method of the invention comprises the following steps: (a) stirring sodium fluosilicate and excessive sulfuric acid at the temperature lower than 150 DEG C for reacting to obtain silicon tetrafluoride gas, wherein hydrogen fluoride remains in solid residues; (b) dedusting, cooling, drying, refining and compressing the silicon tetrafluoride gas generated in the step (a) to obtain high-purity silicon tetrafluoride gas; (c) continuously heating to 200 DEG C to enable the hydrogen fluoride gas to escape; and (d) dedusting, cooling, drying, refining and compressing the hydrogen fluoride gas escaping in the step (c) to obtain the anhydrous hydrogen fluoride (AHF) gas. The invention enables the specific fluorine and silicon resources of phosphate fertilizer enterprises to be fully and efficiently utilized.

Description

technical field [0001] The invention relates to the technical field of fluorine chemical industry, in particular to a method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride gas by reacting sodium fluorosilicate and sulfuric acid. Background technique [0002] Silicon tetrafluoride is an electronic special gas used in semiconductor and optical fiber processing applications, and is an important component in the ion implantation method used in the manufacture of silicon-based semiconductor devices. Silicon tetrafluoride will have broad application prospects in the microelectronics industry. Anhydrous hydrogen fluoride (AHF) is widely used in atomic energy, chemical industry, petroleum and other industries. It is a strong oxidant and a basic raw material for the production of elemental fluorine, various fluorine refrigerants, inorganic fluorides and organic fluorides. [0003] At present, the production methods of hydrofluoric acid in the world are almost al...

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Problems solved by technology

[0003] At present, the production methods of hydrofluoric acid in the world are almost all high-cost, high-energy-consuming, and complex fluorite production processes, and the fluorite resources consumed are extremely limited.

There is no research and industrial test report on the production of hydrofluoric acid from fluosilicic acid and its sodium salt, a by-product of the phosphate compound fertilizer industry, in China; Synthetic calcium fluoride (fluorite) developed by the State Administration of Civil Affairs, and then produce hydrofluoric acid according to the traditional fluorite process. The key conditions of this technology have not yet matured

The second is the sodium bifluoride thermal decomposition method developed by Dublin Chemical Company of Ireland and ISC Chemical Company of the United Kingdom and carried out industrial tests. This process is relatively complicated and has not yet been applied industrially.

The third is the pyrolysis method of fluosilicic acid in the experimental research stage of Swiss Bass Company. This method requires a high concentration of fluosilicic acid, and the concentration of fluosilicic acid by-product of wet phosphate fertilizer (acid) is difficult to achieve.

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